1. Field of the Invention
The present invention relates to apparatus for feeding air into a flotation cell provided with a rotor and a stator. According to the invention, air is fed into the intermediate space formed in between the top covers of the rotor and the stator, above the rotor, wherefrom the air spreads in a symmetrical fashion.
2. Description of Related Art
In the prior art there are known for example the flotation mechanisms introduced in the U.S. Pat. Nos. 4,078,026 and 4,800,017, which comprise a rotor and a stator, and where air is fed through a hollow shaft to inside the rotor, wherefrom it flows out through slurry ducts and aerates the slurry. In both of these U.S. patents, the stator blades of the mechanism are supported against each other by means of a supporting ring, which extends, when seen from the top, to the area of the disc formed by the stator blades.
The Swedish patent publication 398,978 describes a flotation apparatus where around the shaft of a blade mixer there is placed a pipe through which air is sucked into the flotation cell. Around the mixer there is a diffuser with a cover, which diffuser is at its outer edge provided with plates that are arched when observed from the top. On the bottom of the flotation cell, there are placed plates projected in a curved fashion outwards, from the center of the cell towards the periphery thereof, the purpose of which plates is to increase the amount of air sucked in. A similar type of apparatus is also introduced im the SE patent 398,826, but without the plates that regulate the air intake. This blade mixer is not provided with a special cover, but air is mixed with the slurry in similar fashion as the air conducted from within the rotor into the slurry ducts thereof.
The patent publication DE-AS 1,209,971 describes a cell of the Fagergren type, where both the rotor and the stator are formed of blades arranged in a ring. Air is conducted into the cell from around the rotor shaft, and it flows into the space inside the rotor blades through the top part of the rotor.
The U.S. Pat. Nos. 2,865,618 and 3,506,120 also describe feeding of air into the space above the rotor, in between the rotor and the stator, but in both cases the feeding is carried out eccentrically.